Donavon M. Oseid

Factors influencing acute toxicity estimates of hydrogen sulfide to freshwater invertebrates

Abstract Acute bioassay tests of hydrogen sulfide were run on Assellus militaris Hay, Crangonyx richmondensis laurentianus Bousfield. Gammarus pseudolimnacus Bousfield. Bactis vagans McDonough. Ephemera simulans Walker and Hexagenia limbata (Serville). Size and type of test chamber, type of substrate for barrowing forms or those seeking shelter in gravel, oxygen concentration, pH, and season of collection influenced the sensitivity of organisms. Hydrogen sulfide exposure at sublethal levels reduced feeding activity of Gammarus . Data indicate that test conditions should approximate natural habitat conditions as closely as practical. The most acceptable 96-h LC 50 hydrogen sulfide concentrations for the various species are: Assellus 1.07 mg 1 −1 Crangonyx 0.84 mg 1 −1 . Gammarus 0.059 mg 1 −1 . Baetis 0.020 mg 1 −1 . Ephemera 0.316 mg 1 −1 , and Hexagenia , 0.111 mg 1 −1 . Chronic exposure tests now in progress suggest that the no-effect levels are 8–12 per cent of the 96-h LC 50 .

Chronic Toxicity of Hydrogen Sulfide to Gammarus pseudolimnaeus

Abstract Gammarus pseudolimnaeus from two trout streams were exposed to various levels of hydrogen sulfide from 0.0007 to 0.0192 mg/liter in a flow-through apparatus for periods of 65, 95, and 105 days in four tests. Results indicate that 0.002 mg/liter of H2S is the maximum safe concentration for Gammarus, but below this level there is increased reproduction or survival. Mean 96-hr LC50 for Gammarus from the same populations was 0.022 mg/liter of H2S or approximately 10 times the safe level.

Acute toxicity of hydrogen cyanide to freshwater fishes

Acute toxicity of hydrogen cyanide was determined at various temperatures from 4° to 30°C and oxygen concentrations of 3.36 to 9.26 mg/L on different life history stages of five species of fish: fathead minnow,Pimephales promelas Refinesque; bluegill,Lepomis macrochirus Rafinesque yellow perch,Perca flavescens (Mitchill); brook trout,Salvelinus fontinalis (Mitchill); and rainbow trout,Salmo gairdneri Richardson. Median lethal threshold concentrations and 96-hr LC50s were established by flow-through type bioassays. Acute toxicity varied from 57μg/L for juvenile rainbow trout to 191μg/L for field stocks of juvenile fathead minnows. Juvenile fish were more sensitive at lower temperatures and at oxygen levels below 5 mg/L. For most species juveniles were most sensitive and eggs more resistant.

Toxicity of Hydrogen Sulfide to Various Life History Stages of Bluegill (Lepomis macrochirus)

Bluegill (Lepomis macrochirus Rafinesque) eggs, fry, juveniles, and adults were exposed to H/sub 2/S concentrations to determine acute toxicity. Seventy-two-hour LC50 for eggs was 0.0190 ppm, 96-h LC50 for 35-day-old fry was 0.0131 ppm, for juveniles 0.0478 ppm, and for adults 0.0448 ppm. Exposure to lower levels of H/sub 2/S resulted in some acclimation. Chronic exposure to sublethal levels of H/sub 2/S for up to 826 days resulted in no egg deposition at 0.0022 ppm and reduced deposition after 97 days at 0.0010 ppm. Growth was adversely affected at levels from 0.0031 to 0.0107 ppm H/sub 2/S depending on the life history stage at which chronic exposure was started. When exposure was started with eggs, the lower level retarded growth. Food consumption was reduced at 0.0085 ppm H/sub 2/S. Time to anesthesia with MS:222 was reduced at levels from 0.0014 to 0.0031 ppm H/sub 2/S. The most sensitive stage to acute toxicity was the feeding fry and to chronic toxicity was the spawning adult. 10 references, 8 tables.

Swimming Endurance and Resistance to Copper and Malathion of Bluegills Treated by Long-term Exposure to Sublethal Levels of Hydrogen Sulfide

Abstract After 126 or 148 days of exposure to H2S concentrations ranging from .0004 to .0146 mg/1, young-of-the-year bluegills were tested for swimming endurance and resistance to copper or malathion. Swimming tests at low speeds indicated increased endurance for fish exposed to .0004 mg/1 H2S, but fish exposed to higher concentrations had progressively less endurance than the controls. In the tests conducted at higher speeds fish in all test concentrations showed less endurance than the controls. Resistance to copper was increased by exposure to H2S, but resistance to malathion was not affected except in the lowest test concentration. The chronic exposure to H2S also reduced growth in the highest concentration, and gill irrigation rate increased progressively with increased concentrations.

Control of Fungus Growth on Fish Eggs by Asellus militaris and Gammarus pseudolimnaeus

Abstract A test was conducted to evaluate the effect of two invertebrates, Asellus militaris Hay and Gammarus pseudolimnaeus Bousfield, on the growth of fungus, Saprolegnia sp., on walleye eggs, Stizostedion vitreum vitreum (Mitchill). In a second test the effect of the two invertelbrates on mortality of white sucker fry, Catostomus commersonnii commersonnii (Lacepede), was ascertained. Egg mortality was 100% where fungus was not controlled. Both Asellus and Gammarus eliminated fungus-related mortality. Gammarus caused about 15% mortality for both eggs and fry. Asellus did not cause mortality for either stage.